During Hurricane Florence, flood waters from Sutton Lake in Wilmington surrounded Duke Energy’s natural gas plant there, forcing the utility to temporarily shut it down. The utility is citing the historic storm, plus Hurricane Matthew in 2016, as well as other factors, to its need for an extension to close the coal ash impoundments at the plant. (Photo: Duke Energy)

Citing two hurricanes, new and unexpected state requirements, and the challenges of removing the remnants of an old cypress forest in the bottom of a coal ash basin, Duke Energy has asked state environmental regulators for a deadline extension to excavate and close its impoundments at the Sutton plant in Wilmington.

In a 16-page letter to the NC Department of Environmental quality, the utility detailed the difficulties it has encountered over the past four years, as well as its measures to overcome them. If the extension is granted, the new date for closure would be February 2020, six months beyond the original deadline of August 2019.

The utility says it had crews working 20 hours a day, six days a week, in part to dredge the 760,000 cubic yards of material from the 1971 ash basin. Nonetheless, 240,000 cubic yards of dredge material remain, plus 987,500 cubic yards in 1984 basin.

The state’s Coal Ash Management Act allows the secretary of the environment to extend the closure deadline if compliance “can’t be achieved by application best available technology found to economically reasonable at the time and would produce serious hardship without equal or greater benefits to the public.”

Beginning in 2014, Duke Energy transported by rail its first 2 million tons of ash to the Brickhaven mine in Chatham County for structural fill. (This was also controversial: Several citizens groups sued, claiming that new cells were being built to accommodate the ash, and those area should be subject to stricter solid waste permit requirements. The case is still in the courts.)

In 2015, Duke had planned to build a new onsite landfill for 5 million tons of ash from the impoundments, the utility said in its letter, estimating it could excavate 200,000 to 225,000 tons of ash per month, half of which would go to Brickhaven.

But in April 2016, DEQ announced a new policy to conduct an environmental justice review for each ash landfill, which set construction back six months. Nonetheless, Duke says it completed Cells 5 and 6 ahead of schedule, and received leachate permits for the landfill. But as more “air space” opened up in the landfill, it took on more rain, plus water draining from the ash itself. This increased. the amount of leachate from the landfill that needed to be treated.

New state rules requiring a 50-foot buffer on the basin dikes was also “unexpected,” the utility said, adding it could not excavate all of the ash from those dikes until the state approved their removal. That left 125,000 tons of ash, surrounded by water, in the buffer zone of the dikes. Duke then had to “excavate the material” in a less efficient manner.

And finally, last June, the dredgers encountered in the 1971 basin five acres of stumps from an old cypress forest. The debris clogged the machinery, setting the project back another three weeks.

The agency will hold a public meeting on Duke’s request on Jan. 14 at 6 p.m. at Cape Fear Community College, 502 N. Front St., in Wilmington. The public can also comment on the proposal through Feb. 4. Submit them by email to publiccomments@ncdenr.gov. Include the term “Sutton Variance Request” in the email’s subject line.